The actual viability of the dialect continuum has been eroded massively by the codification of Nederlands though; ever since the dialects had a standard language to recourse to, mutual intelligibility across borders will have been eroded. However, there are still reflections of the High German Consonant Shift in some strong dialectal speech in the Netherlands south of the Benrath line - however how often you would hear dialect that broad so as to note this nowadays is pretty debatable.
The dialect continuum to the south is more pronounced at this point. Schwyzertüütsch, if codified, could easily be regarded as a separate language from German. Swiss Standard German is obviously German, with regional variation. The various dialects in Switzerland are almost unintelligible to many Germans (more so than Bavarian-Austrian, though that certainly has its own unique characteristics), especially those from relatively far north who would not typically be exposed to, say, Swabian dialects. In much of Germany (save for those areas with extremely proud regional identities, i.e. Bavaria) the standard language has eroded dialects to the point of curio value, restricted to the villages and almost entirely wiped out from the cities, however the Swiss and to some extent the Austrians display a bit of pride in their dialects as something that is theirs as opposed to imposed from the big bossy country to the north based on a dialect and levelling off producing a standard language entirely unlike any dialect spoken in Switzerland or Austria. However, there has never been a need for the Swiss to codify their language, because everybody is able to use Swiss Standard German to communicate, and therefore Schwyzertüütsch has never become an independent language or sought to (think Lëtzebuergesch).
Within the land habited by people speaking Germanic languages spreading from the Südtirol to the North Sea centuries ago, this was never a situation that could have been faced by the future Dutch; there was no "standard" codified within the Germanic realm, with in many cases Latin still the lingua franca. And the dialect continuum would be repeatedly broken up by politics anyhow.
The dialect continuum to the south is more pronounced at this point. Schwyzertüütsch, if codified, could easily be regarded as a separate language from German. Swiss Standard German is obviously German, with regional variation. The various dialects in Switzerland are almost unintelligible to many Germans (more so than Bavarian-Austrian, though that certainly has its own unique characteristics), especially those from relatively far north who would not typically be exposed to, say, Swabian dialects. In much of Germany (save for those areas with extremely proud regional identities, i.e. Bavaria) the standard language has eroded dialects to the point of curio value, restricted to the villages and almost entirely wiped out from the cities, however the Swiss and to some extent the Austrians display a bit of pride in their dialects as something that is theirs as opposed to imposed from the big bossy country to the north based on a dialect and levelling off producing a standard language entirely unlike any dialect spoken in Switzerland or Austria. However, there has never been a need for the Swiss to codify their language, because everybody is able to use Swiss Standard German to communicate, and therefore Schwyzertüütsch has never become an independent language or sought to (think Lëtzebuergesch).
Within the land habited by people speaking Germanic languages spreading from the Südtirol to the North Sea centuries ago, this was never a situation that could have been faced by the future Dutch; there was no "standard" codified within the Germanic realm, with in many cases Latin still the lingua franca. And the dialect continuum would be repeatedly broken up by politics anyhow.